This invention relates to improvements in brakes of the fail-safe design, i.e., hydraulically-released, spring-engaged disc brakes. These are used primarily in machines and vehicles which are using hydraulic or hydrostatic drive components.
Two of the inherent advantages for using hydraulic drive systems in machinery and vehicles give rise to the need for a brake which is hydraulically released and spring engaged. One is the fact that there is no requirement for a mechanical link between the hydraulically driven motor and the prime mover; instead, the power in a hydraulic drive system is transmitted through relatively vulnerable tubing or hose. Secondly, most hydraulic drive systems can eliminate the need for dynamic brakes because of a hydraulic motor's inherent ability to act as a brake when properly valved.
Thus a failure of a hydraulic component or power transmission lines will result in a vehicle or machine with no dynamic retarding force or emergency lock-up capabilities. Therefore, use of this invention is required in nearly all hydraulic applications for reasons of safety.
Two other characteristics of hydraulic drive systems weighed heavily in the development of this invention and these are:
1. hydraulic systems are by nature very compact for their very high power output;
2. hydraulic systems are modular in concept, i.e., each component is a standalone type of mechanism and a drive system is composed of these various components or modules.